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Title: ELEVATED C02 CONCENTRATION ALLEVIATED WATER STRESS IN CORN (ZEA MAYS L.) CROP

Author
item NIU, GENHUA - USDA-ARS, ACSL
item Timlin, Dennis
item Reddy, Vangimalla
item Kim, Soo Hyung
item Fleisher, David

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 4/29/2004
Publication Date: 4/29/2004
Citation: Niu, G., Timlin, D.J., Reddy, V., Kim, S., Fleisher, D.H. 2004. Elevated c02 concentration alleviated water stress in corn (zea mays l.) crop [abstract]. BARC Poster Day. Abstract No. 18.

Interpretive Summary:

Technical Abstract: Global atmospheric CO2 concentration has been increasing and is expected to be double sometime between the middle and the end of this century. Water stress alone on growth and yield of corn (Zea mays L.) crop has been studied extensively. However, the interaction of water stress and elevated CO2 concentration on corn growth and yield is unclear. The objectives of this study were to quantify the effect of water stress imposed at vegetative and early reproductive stages under ambient and elevated CO2 levels on the photosynthesis and evapo-transpiration of corn plants. The corn plants were grown in the sun-lit SPAR (Soil-Plant-Atmosphere-Research) chambers where temperatures were maintained at 31/25 °C (day/night) under ambient (370 umol mol-1) or elevated (750 umol mol-1) CO2 concentration. Water stress was imposed to plants under ambient and elevated CO2 concentrations, respectively, during vegetative (V10 to V15) and reproductive stage (VT to R1) stages by restricting irrigation. The canopy gross photosynthetic rate (Pg) of the plants under ambient CO2 concentration was reduced by approximately 20% after 18 days without irrigation, while Pg of the plants under elevated CO2 concentration was not reduced. After 30 days without irrigation, Pg of the plants under elevated CO2 was reduced by 10% compared to that of plants under well-watered conditions. Evapo-transpiration rates (ET) of the plants under ambient CO2 concentration decreased as water stress period extended, while ET of the plants under elevated CO2 concentration did not respond to water stress. ET was lower for plants under ambient than elevated CO2 concentrations, regardless of water stress. Water use efficiency of plants was increased under elevated CO2 concentration. Elevated CO2 concentration decreased stomatal conductance to water vapor, which resulted in decreased ET. In summary, elevated CO2 concentration alleviated water stress of corn plants, although no significant enhancement was observed in photosynthesis.